This invention relates to the use of non- or low-metabolizable substances to kill pests, especially insects.
Pesticides in common use depend upon general or specific toxicity of one or more ingredients to one or more species, or groups, of pests. In many instances, broad or specific pest attractants, ranging from relatively simple odorants to pheromones, are incorporated into the pesticide to induce the pests to take the bait including the active pesticide ingredients.
Unfortunately, in most cases, the antimetabolic or toxic effects which make the pesticides effective may also be effective against desirable species, including man, when ingested or inhaled. Lethal human exposures have occurred to workers manufacturing pesticide ingredients, workers combining active ingredients with attractants and/or packaging the product, pesticide applicators in fields or buildings and bystanders inadvertently exposed or who ingested the pesticides deliberately, as in the case of children, or accidently without knowing the effects. Another classic problem with many pesticides is the gradual adaptation of the pests rendering them immune or resistant.
Pesticides also find their way into surface waters and groundwater as the result of extensive broadcasting of these materials in combating infestations of pests or in preventing pests from achieving destructive or nuisance levels in numbers. In recent years, increasing attention has been paid to the effect of such chemical contamination of surface or subsurface derived potable waters. Some such pesticides can travel great distances in surface or subsurface waters and can persist at concentrations harmful to man. Accordingly, the EPA and other agencies have established toxicity levels for these materials which must not be exceeded in food and potable waters. The limits imposed result from the typical risk/benefit ratio type of analysis for which accurate scientific and economic parameters are difficult to establish.
U.S. Pat. Nos. 4,279,895 and 4,386,071, both to Carle, disclose insecticidal compositions based on diatomaceous silica and a sugar. The '895 patent states that the insect is attracted to the composition by the sugar which is impregnated in the pores of the diatomaceous silica. The insects thereafter swallow the composition because they are attracted to the sugar. Tests on dead insects after eating the composition reveal that their bowels are perforated, which results in rapid death followed by desiccation. The active agent in this case is the diatomaceous silica.
It is an object of this invention to avoid hazards to humans and other beneficial, desirable species while still providing adequate pest control and doing so through a mechanism against which adaptive immunity is extremely unlikely or impossible.